How to Check If a Reverse DNS PTR Record Was Added

PTR records are used by spam filters to verify DNS names have legitimate IP addresses.

Configure your Domain Name Service (DNS) servers to include reverse DNS Pointer (PTR) records, especially for DNS records that will be used by email servers so your email does not get blocked by spam filters. Unlike DNS "A," "CNAME" or "MX" records that resolve a DNS name to an IP address, PTR records resolve an IP address to a DNS name. Use the "Dnscmd" command line tool included with Windows Server 2008 to verify a reverse DNS PTR record is configured.

Things You'll Need

• Microsoft Windows Server 2008 with the DNS server role installed and configured
• Credentials of an account that has Administrator permissions on the Windows Server 2008 computer
• IP address of the Windows Server 2008 computer
• DNS zone containing the PTR record that must be tested

Instructions

1. Log into the Windows Server 2008 computer using the user name and password of an account that has Administrator permissions on the computer.

2. Click the "Start" button on the Windows desktop taskbar, click the "Search" box, type "cmd" in the "Search" box and press the "Enter" key. The command line window will appear.

3. Type "dnscmd x.x.x.x /enumrecords zone_name" at the command prompt, except replace "x.x.x.x" with the IP address of the DNS server and replace "zone_name" with the DNS zone that contains the PTR record you wish to test.

4. Press the "Enter" key. View the command line output and verify the PTR record you wish to check is in the list of records displayed.

References

• Microsoft Technet: Dnscmd
• MSMVPs: DNSCMD References
• Email Talk: Reverse PTR Records